This invention relates to deflection systems operable either from alternating current line voltage or from storage batteries.
A portable television receiver capable of being operated from an alternating current line voltage supply or alternatively from a battery supply typically develops direct current operating voltage by rectifying a relatively low voltage obtained from a step-down transformer. When the receiver is operated in the line voltage mode, the transformed alternating current line voltage may be rectified and filtered to develop direct current operating voltage substantially equal to the battery voltage. This direct current operating voltage usually is supplied through a winding of the horizontal output transformer to the horizontal deflection output stage which typically includes a power transistor. Current flow induced in a primary winding of the horizontal output transformer as the horizontal deflection system operates from this potential supply may then be used to induce voltage variations in other windings of the horizontal output transformer. The induced voltage variations may be rectified and filtered to supply additional direct current potentials to other receiver circuits.
When the receiver is operated in the battery mode, substantially the same direct current operating voltage is supplied to the same point on the horizontal output transformer from the battery and current flow induced in the horizontal output transformer primary winding by the action of the horizontal deflection system produces similar voltage variations which are rectified and filtered to create direct current voltage supplies at other potentials necessary for the operation of other receiver circuits.
Use of such a system requires that an expensive bulky step-down transformer be used to reduce the alternating current line voltage supply to the battery supply voltage. Attempts have been made to drop the voltage directly from rectified alternating current line potential to battery potential which may be supplied directly to the horizontal output transformer. Schemes involving this approach have met with little success, however, since the rectified alternating current line voltage must be dropped considerably in potential to approximate the voltage available from battery supplies commonly used with batteryor line-operated portable television receivers. Such a voltage dropping technique results in substantial power losses due to the flow of current through resistive elements.